Direct-print silver halide emulsions

ABSTRACT

DIRECT-PRINT SILVER HALIDE EMULSIONS COMPRISING THE COMBINATION OF A URAZOLE HALOGEN ACCEPTOR AND A MEROCYANINE DYE HAVING CARBOXY-CONTAINING SUBSTITUENTS THEREON PROVIDE IMPROVED PHOTOGRAPHIC SYSTEMS HAVING BETTER IMAGE PROPERTIES SUCH AS, FOR EXAMPLE, IMPROVED IMAGE DISCRIMINATION UPON STORAGE.

United States Patent 3,579,348 DIREQT-PRTNT SILVER HALIDE EMULSIONS Delbert Dale Fix and Richard Warren Karlson, Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y. No Drawing. Filed Oct. 21, 1966, Ser. No. 588,342 Int. Cl. G03c 1/08, 1/10, 1/28 US. Cl. 96l26 14 'Claims ABSTRACT OF THE DISCLOSURE Direct-print silver halide emulsions comprising the combination of a urazole halogen acceptor and a merocyanine dye having carboXy-containing substituents thereon provide improved photographic systems having better image properties such as, for example, improved image discrimination upon storage.

The present invention relates to photography. In one aspect this invention relates to novel photographic compositions. In another aspect this invention relates to lightdevelopable or direct-print photographic silver halide emulsions.

Radiation-sensitive papers adapted for light recording, e.g., oscillographic recording, are known. Typical of such papers are the developing-out and print-out type. The developing-out type as the name implies, requires that the exposed material be chemically developed, fixed and washed in order to provide a stable visible image on said material. The print-out type of material develops on exposure and requires no development step. The print-out type is generally much slower than the developing-out type and the images are unstable and have a short life.

A third type of radiation-sensitive material especially suitable for light-writing and oscillographic recording comprises a hydrophilic colloid-silver halide emulsion layer which, when exposed to a high intensity source of electromagnetic radiation, forms a latent image which can then be developed by subsequent general exposure to a second source of radiation of lower intensity. Such direct- Writing or direct-print emulsions are faster than print-out emulsions and require no chemical development. However, many of the recording papers of this third type have a slow rate of photodevelopment and the background areas tend to build up to obscure the image on subsequent exposure to light.

It is known in the art of light-developable or directprint silver halide emulsions to employ halogen acceptors in the emulsions. Urazole compounds have been found to be very effective as halogen acceptors to provide a resultant direct-print with a relatively high density image and a low density background. However, the image quality and high image discrimination properties upon photodevelopment of an emulsion containing a urazole compound as a halogen acceptor are partially lost through some type of degradation during the storage time before using the photographic element.

It is accordingly an object of this invention to provide new direct-print, radiation-sensitive silver halide compositions.

It is another object of this invention to provide novel photographic silver halide emulsions suitable for preparing direct-print recording paper having a high rate of photodevelopment.

3,579,348 Patented May 18, 1971 It is another object of this invention to provide novel photographic, direct-print, silver halide emulsions that have improved image properties when stored for a period of time before photodevelopment.

It is another object of this invention to provide novel, photographic, direct-print silver halide emulsions that can be exposed and photodeveloped after several weeks of storage to produce a high density image with a comparatively low density background.

It is another object of this invention to provide novel photographic light-developable, direct-print silver halide emulsions that can be chemically developed and fixed before or after photodevelopment to make archival-quality records.

It is another object of this invention to provide new photodevelopable photographic silver halide emulsions that are characterized as having high density differential between the initially-exposed and unexposed areas upon subsequent photodevelopment.

It is also an object of this invention to provide new light-developable photographic silver halide emulsions that have high resistance in the initially-unexposed areas to density increase upon photodevelopment and subsequent exposure to light.

It is also an object of this invention to provide a means for retarding degradation of a direct-print silver halide emulsion containing a urazole halogen acceptor.

Other objects will become apparent from the description and claims to this invention.

These and other objects of this invention are accomplished with direct-print, radiation-sensitive silver halide compositions comprising a urazole halogen acceptor in combination with certain chemical additives which retard degradation with respect to storage time. Additives which have been found to be effective for this purpose are certain classes of merocyanine dyes, as hereinafter described.

The urazoles which can be utilized include those which are effective as halogen acceptors in the light-developable, direct-print photographic silver halide emulsions. Suitable halogen acceptors can be represented by the formula wherein X and Z can each be an oxygen atom, a sulfur atom, a selenium atom, or an imino radical NH); and R R and R can each be a hydrogen atom, an aryl radical such as naphthyl or phenyl, an amino radical (NH or an alkyl radical typically having 1 to 20 carbon atoms, and more generally, 1 to 8 carbon atoms, such as methyl, ethyl, propyl, butyl, amyl, octyl, decyl, dodecyl, octadecyl, eicosyl, etc., except that at least one of R and R is a hydrogen atom. Thiourazoles, that is, compounds wherein at least one of X or Z is a sulfur or oxygen atom are particularly useful halogen acceptors. Also, salts of the urazoles can be utilized. Urazoles, being acidic materials, form organic or inorganic salts with basic materials, such salts being suitably used as addenda in the present emulsions. Typical of such salts are sodium, hydrazine, ammonium and the like.

Illustrative urazoles that can be utilized either alone or in admixture, as halogen acceptors in the silver halide emulsions of the invention include:

urazole 3-thiourazole 3,5-dithiourazole 3,5-dithiourazole hydrazine salt 4-aminou1'azole hydrazine salt 3,5-dithiourazole hydrazine salt urazole sodium salt 4-( l-naphthyl) urazole 4-ethylurazole l-phenylurazole 4-phenylurazole l-butylurazole l-octylurazole 4-butyl-3,S-dithiourazole 1,4-diphenylurazole 1,4-dibutylurazole l,4-dibutyl-3,S-dithiourazole 1,4-diphenyl-3,S-dithiourazole l-ethyl-4-phenylurazole 1-ethyl-4-phenyl-3,S-dithiourazole 3-thio-5-iminourazole 3,5-diselenourazole The concentration of urazoles utilized in the emulsions of the invention can be widely varied in accordance with usual practice. Generally, about .1 to 100 mole percent, and preferably about 1 to 50 mole percent, based on the silver halide in the emulsion, of urazole is utilized.

The merocyanine dyes employed in the practice of this invention are those which contain a carboxy substituent. Suitable dyes can be represented by the formula:

O=C-N-R R -1-'1 oH=orr m ,-o- =o-o n=o O=X R R Y wherein X can be a sulfur or a selenium atom; R and R can be carboxy radicals or carboxyalkyl radicals; R R R and R can be an alkyl radical (e.g., methyl, ethyl, carbethoxymethyl, benzyl (phenylmethyl), fl-sulfoethyl, butyl, etc.), an aryl radical, such as phenyl, tolyl, etc., and R R and R can also be a hydrogen atom; Y is an oxygen atom, a sulfur atom, a selenium atom,

wherein R can be any of the substituents of R and at least one of the substituents R R and R is a carboxy or carboxyalkyl group in the useful dyes of this invention; In is a positive integer of 1 or 2 and preferably 1; n is a positive integer of 0, 1 or 2; and Z represents the nonmetallic atoms required to complete a basic heterocyclic nucleus generally having 5 to 6 atoms in the heterocyclic ring such as carbon, sulfur, selenium, oxygen and nitrogen to form such moieties as those selected from the group consisting of those of the thiazole series (e.g., thiazole, 4- methylthiazole, S-methylthiazole, 4-phenylthiazole, 5- phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl)thiazole, etc.), those of the benzothiazole series (e.g., benzothiazole, 4-chlorobenzothiazole, S-chlorobenzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole, S-methylbenzothiazole, 6- methylbenzothiazole, S-bromobenzothiazole, 6-bromobenzothiazole, 4-phenylbenzothiazole, S-phenylbenzothiazole, 4-methoxybenzothiazole, S-methoxybenzothiazole, 6-methoxybenzothiazole, 5 iodobenzothiazole, 6 iodobenzothiazole, 4 ethoxybenzothiazole, 5 ethoxybenzothiazole, tetrahydrobenzothiazole, 5,6-dimethoxybenzothiazole, 5,6- dioxymethylenebenzothiazole, 5 hydroxybenzothiazole, 6 hydroxybenzothiazole, etc.), those of the naphthothiazole series (e.g., a naphthothiazole, fi naphthothiazole, 5-meth0xy- 3-naphthothiazole, 5 ethoxy-B-naphthothiothiazole, 7 methoxy-a-naphthothiazole, 8 methoxya-naphthothiazole, etc.), those of the thianaphtheno-7',6', 4,5-thiazole series (e.g., 4'-methoxythianaphtheno-7',6',4, S-thiazole, etc.), those of the oxazole series (e.g., 4-methyloxazole, S-methyloxazole, 4 phenyloxazole, 4,5-diphenyloxazole, 4-ethyloxazole, 4,5 dimethyloxazole, S-phenyloxazole, etc.), those of the benzoxazole series (e.g., benzoxazole, 5 chlorobenzoxazole, S-phenylbenzoxazole, 5 methylbenzoxazole, 6 methylbenzoxazole, 5,6 dimethylbenzoxazole, 4,6-dimethylbenzoxazole, 5 methoxybenzoxazole, 6-methoxybenzoxazole, S-ethoxybenzoxazole, 6- chlorobenzoxazole, 5 hydroxybenzoxazole, 6-hydroxybenzoxazole, etc.), those of the naphthoxazole series (e.g., a-naphthoxazole, 13 naphthoxazole, etc.), those of the selenazole series (e.g., 4-methylselenazole, 4-phenylselenazole, etc.), those of the benzoselenazole series (e.g., benzoselenazole, 5 chlorobenzoselenazole, 5 methoxybenzoselenazole, 5 hydroxybenzoselenazole, tetrahydrobenzoselenazole, etc.), those of the naphthoselenazole series (e.g., tat-naphthoselenazole, 5 naphthoselenazole, etc.), those of the thiazoline series (e.g., thiazoline, 4-rnethylthiazoline, etc.), those of the 2-quinoline series (e.g., quinoline, 3-methylquinoline, S-methylquinoline, 7-methylquinoline, S-methylquinoline, 6-chloroquinoline, 8-chloroquinoline, 6-methoxyquinoline, 6 ethoxyquinoline, 6- hydroxyquinoline, 8 hydroxyquinoline, etc.), those of the 4-quinoline series (e.g., quinoline, 6 methoxyquinoline, 7 methylquinoline, 8 methylquinoline, etc.), those of the l-isoquinoline series (e.g., isoquinoline, 3,4-dihydroisoquinoline, etc.), those of the 3,3-dialkylindolenine series (e.g., 3,3-dimethylindolenine, 3,3,5-trimethylindolenine, 3,3,7-trimethylindolenine, ete.), those of the 2- pyridine series (e.g., pyridine, 3-methylpridine, 4-methylpyridine, S-methylpyridine, 6-methylpyridine, 3,4-dimethylpyridine, 3,5-dimethylpyridine, 3,6-dimethylpyridine, 4,5 dimethylpyridine, 4,6 dimethylpyridine, 4- chloropyridine, S-chloropyridine, 6-chloropyridine, 3-hydroxypyridine, 4-hydroxypyridine, S-hydroxypyridine, 6- hydroxypyridine, 3-phenylpyridine, 4-phenylpyridine, 6- phenlpyridine, etc.), those of the 4-pyridine series (e.g., Z-methylpyridine, 3-methylpyridine, 2-chloropyridine, 3- chloropyridine, 2,3-dimethylpyridine, 2,5-dimethylpyridine, 2,6-dimethylpyridine, Z-hydroxypyridine, 3-hydroxypyridine, etc.), those of the l-substituted imidazole series (e.g., l-ethylimidazole, 1-ethyl-4-phenylimidazole, 1,4-dimethylimidazole, 4 methyl phenylimidazole, etc.), those of the 1-substituted benzimidazole series (e.g., 1- ethylbenzimidazole, l-butylbenzimidazole, l-ethy1-4,5-dichlorobenzimidazole, etc.), those of the l-substituted naphthimidazole series (e.g., l-methyl a naphthimidazole, l-ethyl a naphthimidazole, l-butyl-fi-naphthimidazole, 6-chloro-l-methyl-u-naphthimidazole, etc.), etc. The Y substituent is preferably to form a thiohydantoin nucleus. When Y is a sulfur atom, the heterocyclic moiety completed by the substituent Z is other than a thiazoline group,

when n is l.

The alkyl substituents in the described dyes can be widely varied although alkyls having 1 to 18 carbon atoms are more generally used, i.e., those alkyl denominated lower alkyls having 1 to 4 carbon atoms and those alkyls denominated higher alkyls having 5 to 18 and preferably 7 to 18 carbon atoms. The alkyl and aryl radicals of the described dyes can be substituted or unsubstituted.

A preferred class of carboxy or carboxyalkyl substituted merocyanine dyes used to retard degradation in the compositions of the invention are merocyanine dyes having a first nucleus such as thiazoline, thiazole, benzoxazole, naphthoxazole, pseudoindole, benzimidazole, benzothiazole, naphthothiazole, pyridine, quinoline, and etc., and a second nucleus such as thiohydantoin, rhodanine, thio-oxazolidinedione and etc., wherein a carboxy or carboxyalkyl radical is substituted on either the first or second nucleus.

Illustrative merocyanine dyes that can be utilized either alone or in admixture in combination with the sillvgr halide-urazole compositions of this invention inc u e:

3 -carboxymethyl--[ 3-ethyl-2 (3 -benzoxazolylidene ethylidene] rhodanine 5- l- (Z-carboxyethyl) -4-( 1H) -pyridylidene]-3-ethyl rhodanine 3-carboxymethyl-5- (3-ethyl-2 (3 -benzothiazolylidene) rhodanine 3-carboxypropyl-5- 1-ethylnaphtho( 1,2-d) thiazolin-2- ylidene -1-methylethylidene] rhodanine 3-( 1,3-dicarboxy) -n-propyl-5-[ (3-ethyl-2 (3 -benzothiazolylidene)-ethylidene] rhodanine 3-carboxymethyl-5-[ (3-methyl -2 (3 )-thiazolinylidene) ethylidene] -2-thio-2,4- 3 ,5 -ox-azole dione 1-carboxymethyl-5-[ (3-ethyl-2 3 )-benzoxazolylidene) ethylidene] -3 -phenyl-2-thiohydantoin 3-carboxymethyl-5- 3-ethyl-2( 3 -benzothiazolylidene isopropylidene] -2-thio-2,4 3 5 -oxazoledione Additional illustrative dyes are structurally depicted in the examples for a ready comparison of the carboxy substituted dyes with the non-carboxy substituted dyes.

The concentration of the dyes used in the silver halide compositions can be widely varied. Most of the dyes which are effective in retarding degradation of the urazole-silver halide compositions are also effective sensitizing dyes to extend the sensitivity of the composition to radiation wavelengths over a wider spectrum than the normal sensitivity of silver halide. Thus, the concentration of the dyes will vary according to the type of emulsion and according to the effect desired. The suitable and most economical concentration for any given emulsionwill be apparent to those skilled in the art upon making the ordinary tests and observations customarily used in the art of emulsion making. Generally, about to about 1000 mg. of dye per mole of silver halide in the emulsion are utilized. About .05 to about 1 mole percent of the dye based on the silver halide in the emulsion is a typical working range to provide both diminished degradation of the urazole-silver halide composition together with increased spectral sensitivity. A single dye or combinations of several dyes can be used in the present compositions.

A wide variety of direct-print photographic silver halide emulsions can be utilized in the invention, such being well known to those skilled in the art. Suitable silver halides include silver chloride, silver bromide, silver bromoiodide, silver chloroiodide, and silver chlorobromoiodide. The preferred emulsions are those wherein the silver halide is predominantly bromide. For a description of suitable emulsions, reference is made to Davey et al., US. Pat. 2,592,250, issued Apr. 8, 1952; Glafkides, Photographic Chemistry, vol. 1, pp. 31-2, Fountain Press, London; and McBride, US. Pat. 3,271,157, issued Sept. 6, 1966, wherein is disclosed the preparation of silver halide emulsions with organic thioether silver halide solvents present during the grain growth of the silver halide. In the McBride patent is taught the addition of the thioether silver halide solvent to the colloidal material in which the silver halide is precipitated, during the precipitation of the silver halide or to the silver halide prior to or during the ripening of the silver halide. Typical of such thioethers are 3,6-dithia-1,8-octanediol, 1,10-dith1a- 4,7,13,16 tetraoxacyclooctadecane, 7,10 diazo-1,16-dicarboxamido-3,l4-dithiahexadecane-6,1l-dione, and 1,17- di-(N-ethylcarbamyl)-6,12-dithia-9-oxaheptadecane. The amount of thioether utilized to prepare the silver halide emulsions described in the McBride patent can be widely varied although about .1 to 25 g. of thioether per mole of silver halide is generally utilized. The present silver halide emulsions generally have an average grain size of about .1 to 10 microns, and more generally about .5 to 1 micron.

The so-called internal image emulsions can be used in the invention, such having silver halide grains wherein a predominant amount of the sensitivity is internal to the grains. Such internal image emulsions are those which, when measured according to normal photographic techniques by coating a test portion of the emulsion on a transparent support, exposing to a light intensity scale having a fixed time between 1 10- and 1 second bleaching 5 minutes in a 0.3% potassium ferricyanide solution at 65 F. and developing for about 5 minutes at 65 F. in Developer B below (an internal-type developer), have a sensitivity, measured at a density of 0.1 above fog, greater than the sensitivity of an identical test portion which has been exposed in the same way and developed for 6 minutes at 68 F. in Developer A below (a surface-type developer).

DEVELOPER A G. N-methyl-p-aminophenol sulfate 0.31 Sodium sulfite, desiccated 39.6 Hydroquinone 6.0 Sodium carbonate, desiccated 18.7 Potassium bromide 0.86 Citric acid 0.68 Potassium metabisulfite 1.5 Water to make 1 liter.

DEVELOPER B G. N-methyl-p-aminophenol sulfate 2.0 Sodium sulfite, desiccated 90.0 Hydroquinone 8.0 Sodium carbonate, monohydrate 52.5 Potassium bromide 5.0 Sodium thiosulfate 10.0 Water to make 1 liter.

Various colloids can be used as vehicles or binding agents in preparing the silver halide emulsions of this invention. Satisfactory colloids which can be used for this purpose include any of the hydrophilic colloids generally employed in the photographic field, including, for example, gelatin, colloidal albumin, polysaccharides, cellulose derivatives, synthetic resins such as polyvinyl compounds, including polyvinyl alcohol derivatives, acrylamide polymers and the like. In addition to'the hydrophilic colloids, the vehicle or binding agent can contain hydrophobic colloids such as dispersed polymerized vinyl compounds, particularly those which increase the dimensional stability of photographic materials. Suitable compounds of this type include water-insoluble polymers of alkyl acrylates or methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates and the like.

The photographic silver halide emulsion made accord ing to this invention can be hardened with any suitable hardener including aldehyde hardeners; preferably polyfunctional hardeners having two or more reactive groups which will react with gelatin are used as hardeners such as mucochloric acid, gluteraldehydes, aziridine hardeners, hardeners which are derivatives of dioxane, oxy polysaccharides such as oxy starch, oxy plant gums such as oxy guar gum, and the like.

Lead ions can be used in the precipitation or formation of the silver halide used in the emulsions of the invention. Water-soluble lead salts are typically added with a water-soluble silver salt to an appropriate water-soluble halide to precipitate a lead-silver halide. The concentration of lead used in the present silver halide emulsions typically ranges from about .01 to mole percent based on the silver.

Although silver halide emulsions are generally made with an equivalent or slight excess of halide ion present, additional water-soluble iodide to the silver halide emulsion after its precipitation but before it is coated can be added. More generally about .1 to 50 mole percent, and preferably about 1 to mole percent of water-soluble iodide based on the silver halide in the emulsion is used. Illustrative water-soluble iodides include ammonium, calcium, lithium, magnesium, potassium, or sodium iodide.

The subject photodevelopable photographic silver halide emulsions of the invention can contain other halogen acceptors in addition to the feature urazole compounds described above, the addenda generally utilized in such products including gelatin plasticizers, coating aids and the like. as well as spectral sensitizing dyes of the type described in copending Jones application, now US. Pat. 3,364,032 issued Jan. 16, 1968, and other spectral sensitizing dyes known in the art.

The emulsions of the invention can be coated on a wide variety of supports in accordance with usual practice. Typical supports for photographic elements of the invention include paper, cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethyleneterephthalate film and related films of resinous materials and others.

In forming a photodeveloped image with a typical photographic element containing an emulsion of the invention, the photographic element is initially exposed to a relatively short duration and high intensity source of electromagnetic radiation (e.g., at least about .1 foot-candle second at an intensity of more than about 100-foot candles) such as a high intensity light source rich in blue and ultraviolet light such as are used in oscillographs described in Heiland, U.S. Pat. 2,580,427, issued Jan. 1, 1952, high intensity visible light, X-radiation and the like, to form a latent image in the emulsion of the photographic element, and thereafter the resulting latent image is photodeveloped by over-all exposure of the emulsion to a radiation source of lower intensity than the original exposure, such as to a conventional fluorescent light, light from incandescent lamps commonly used for general illumination, or even ordinary daylight. Generally, the latent image formed in the emulsion in the first instance is not visible and does not become visible until photodevelopment. Heat is desirably utilized during the photodevelopment step. Typically the subject emulsions are heated to a temperature of about 90 C. to 200 C. for about 1 to 30 seconds and photodeveloped after the initial high intensity exposure.

If desired, photographic elements containing the emulsions of the invention can be developed and fixed in aqueous chemical developing-out and fixing solutions after the initial exposure forming the latent image, or after the above-described photodevelopment, to make archivalquality records.

The invention can be further illustrated by the following examples, although it will be understood that the examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise indicated.

EXAMPLE 1 The results of incubation tests described herein demonstate the effect of a carboxy substituted merocyanine dye on the image properties with respect to storage time when said dye is incorporated in a direct-print silver halide emulsion containing a urazole halogen acceptor.

A direct-print, radiation sensitive, gelatino silver chlorobromide emulsion (98 mole percent bromide and 2 mole percent chloride) having silver halide grains of high internal sensitivity is prepared by the procedure as described in Example 1 of McBride, US. Pat. 3,271,157 issued Sept. 6, 1966. The emulsion is washed and mixed with a gelatin solution to produce an emulsion containing about 200 grams of gelatin/mole of silver halide in the emulsion.

To 173 g. of this emulsion containing 0.07 mole of silver is added 35 ml. of a solution containing 40 mg. of urazole per ml., plus conventional coating aids. An additional preparation is made as above, 'but has in addition to the above, 12.5 ml. of a solution containing 1 mg. of 3 carboxymethyl 5 [(3 ethyl 2(3)-benzoxazolylidene)-ethylidene] rhodanine (Dye I) per ml. mg./ mole of siver). The respective preparations are coated on single Weight photographic paper at 256 mg. of silver per ft. and 558 mg. gelatin/ft After drying, part of each coating is incubated one week at 49 C., 35% RH. Samples from both the incubated and non-incubated portions are exposed through a step tablet with 0.15 density increments in an Edgerton Germishausen and Greer Mark 6 xenon flashlamp sensitometer at the 10* sec. setting. The exposed samples are photodeveloped by exposing them over-all for five minutes to 50 PC. of cool white fluorescent light. D and D are measured in a reflection densitometer. The results of the tests are as follows:

Fresh test Incubation Percent Dmin. Dmnx. AD Dmin. Dmax. AD 1055 Dye:

None .20 .64 .44 .17 .46 .29 34 (I) 26 .77 51 .21 .66 .45 12 EXAMPLE 2 The carboxy substituted merocyanine dyes are more effective in preventing loss of image properties than the respective alkyl substituted dyes. To illustrate, three thiohydantoin-type dyes represented by the following formulas are incorporated into silver halide-urazole emulsions and tested.

A direct-print, radiation sensitive gelatino silver chlorobromide emulsion (about 98 mole percent bromide and about 2 mole percent chloride) having silver halide grains of high internal sensitivity is prepared by the procedure described in Example of McBride, US. Pat. 3,271,157 issued Sept. 6, 1966, including the use of lead nitrate and a thioether during the preparation.

Using this emulsion, three preparations are :made up coated and tested as in Example I using Dyes II, III and IV respectively at the concentration preformed as in Example I. Results of tests are as follows:

Fresh test Incubation Percent loss in Dmiu, Dmax. AD Dmin. Dmax. AD AD Dye:

II .30 .64 .34 .31 .55 .24 29 III 28 61 33 .30 54 24 27 IV .26 .54 .28 .27 .43 .16 43 The carboxy substituted merocyanine dyes having a rhodanine nucleus are also more effective in preventing loss in image properties than the respective alkyl substituted compounds.

Silver halide emulsions are prepared by the method of Example 1 and dyes represented by the following formula are incorporated into the emulsion.

( lzHi The emulsions are coated and tested 'by the procedure set forth in Example 1. Results of the tests are as follows:

Fresh test Incubation Percent loss in Dmin. Dmax. AD Dmin. Dmax. AD AD Dye:

V .21 .77 .56 .21 .65 .44 21 VI .21 .77 .56 .21 .68 .47 16 It is apparent that merocyanine dyes containing the rhodanine nucleus are effective in retarding loss in image discrimination upon storage.

When the carboxy group is on the benzothiazole group of the above dye similar improvement in the incubation test results are observed. Likewise, carboxy groups substituted on the thiazoline, thiazole, benzoxazole, naphthoxazole, pseudoindole, benzimidazole, naphthiazole, pyridine and quinoline groups of the respective merocyanine dyes show improved results in incubation tests as compared with the respective non-carboxy substituted dyes.

The invention has been described with reference to certain embodiments thereof for purposes of comparison of the compounds of the invention, but it will be understood that variations and modifications of the invention can be made within the scope of the following claims.

We claim:

1. A direct-print silver halide emulsion comprising a urazole halogen acceptor and a merocyanine dye having carboxy-containing substituents, said dye having the following formula:

wherein (a) I is an oxygen atom, a sulfur atom, a selenium atom or a group having the formula (b) R R and R are each an alkyl radical, an aryl radical, a hydrogen atom, a carboxy radical or a carboxyalkyl radical, provided that at least one of R R and R is a carboxy or carboxyalkyl radical,

(c) R and R are each an alkyl radical, an aryl radical or a hydrogen atom,

(d) Q represents the atoms required to complete a basic heterocyclic nucleus, Q being other than the atoms required to complete a thiazoline group when I is a sulfur atom,

(e) m is a positive integer of 1 to 2,

(f) n is a positive integer of 0 to 2, and

(g) W is a sulfur atom or a slenium atom.

2. An emulsion according to claim 1 which comprises silver halide grains formed in the presence of lead ions.

3. A composition according to claim 2 which comprises silver halide grains grown in the presence of an organic thioether.

4. An emulsion according to claim 1 which contains a water soluble iodide.

5. An emulsion according to claim 1 which comprises a silver chlorobromide emulsion having a predominant amount of radiation sensitivity internal to said grains.

6. An emulsion according to claim 1 wherein said merocyanine dye contains a thiohydantoin nucleus.

7. An emulsion according to claim 1 wherein said merocyanine dye contains a rhodanine nucleus.

8. An emulsion according to claim 1 wherein said merocyanine dye contains a thio-oxazolidinedione nucleus.

9. An emulsion according to claim 1 wherein said merocyanine dye is 5-[1-(2-carboxyethyl)-4(1H)-pyrilylidene]-3-ethyl-rhodanine.

10. An emulsion according to claim 1 wherein said merocyanine dye is 3-carboxypropyl-5-[(l-ethylnaphtha- (1,2-d) thiazolin-Z-ylidene) 1 methylethylidene] rhodamne.

11. An emulsion according to claim 1 wherein said merocyanine dye is 3-carboxymethyl-5-[(3-ethyl-2(3)- benzoxazolylidene) ethylidene] rhodanine.

12. An emulsion according to claim 1 wherein said silver halide comprises silver chlorobromide grains formed in the presence of lead ions, said halogen acceptor is urazole and said merocyanine dye has a rhodanine nucleus.

13. A direct-print silver halide emulsion comprising (a) a urazole halogen acceptor having the formula:

wherein each X and Z are each an oxygen atom, a sulfur atom, a selenium atom, or an imino radical; and R R and R are each a hydrogen atom, an alkyl radical, an aryl radical, or an amino radical, provided that at least 1 1 one of R and R is a hydrogen atom and (b) a merocyanine dye having the formula:

O=G--NR (a) J is an oxygen atom, a sulfur atom, a selenium atom or a group having the formula (b) R R and R are each an alkyl radical, an aryl radical, a hydrogen atom, a carboxy radical or a carboxyalkyl radical, provided that at least one of R R", and R is a carboxy or carboxyalkyl radical,

(c) R and R are each an alkyl radical, an aryl radical,

or a hydrogen atom,

(d) Q represents the atoms required to complete a basic heterocyclic nucleus, Q being other than the atoms required to complete a thiazoline group when J is a sulfur atom,

UNITED STATES PATENTS 3,396,017 8/1968 Bacon et al. 96-107 2,493,747 1/ 1950 Brooker et al. 96-102 2,493,748 1/1950 Brooker et al. 96102 2,519,001 8/1950 Sprague 96102 3,271,157 9/1966 McBride 96-107 3,287,136 11/1966 McBride 96119 NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant Examiner US. Cl. X.R. 96-106, 107 

